He was arrested by the FBI inside a building without incident, according to the sources, who asked not to be named because they were not authorized to speak on the matter. The details surrounding his arrest were unclear Wednesday night.

The FBI in Los Angeles declined to comment.

The arrest came as the FBI launched a media campaign in 14 cities to help determine Bulger's whereabouts.

The last credible sighting of Bulger was in London in 2002, the FBI said.

Photo: A poster featuring fugitives James "Whitey" Bulger and Catherine Greig is on display Monday at a news conference in Boston at which the FBI announced TV ads aimed at finding the mob boss and his mistress. Credit: Associated Press